U.S. Pat. No. 4,940,065 describes an electrode adapted to be implanted surgically around a nerve bundle to provide selective: stimulation acting on certain parts of the nerve concerned.
The electrode comprises a biocompatible and dielectric carrier that starts from an open position and can be flattened to a closed position, completely encircling the nerve bundle, resulting in a constraint for postoperative inflammatory problems.
In its open position the carrier appears as a main body portion extending in the direction of a longitudinal winding axis of the carrier and flap portions extending transversely and outwardly from the opposite ends of the carrier. At least one electrode contact is fixed to an inner surface of the carrier and is welded to a conductive wire adapted for connection to a receptor implanted on the patient. As far as the method steps to manufacture the electrode are concerned, the carrier is originally a tube that is properly cut to form the main body and its flap portions. The contact of the electrode is then attached to an inner surface of the support and is welded to the conductor wire. It does not include a fixing device, i.e. the electrode can slide inducing the modification of the stimulation parameters.
ATROTECH company, acting under the trademark of “Atrostim”, has designed an electrode which comprises two pairs of contactors arranged symmetrically around the nerve at a certain distance from one another on the longitudinal plane thereof.
During the stimulation sequence, which applies a combination of four electrical currents, the two opposite activated poles serve as cathode and anode and vice versa.
This results in the four combinations of stimulating actions generating low value electric currents.
This technology was developed to reduce the stressed nerve fatigue as it envisages activation of its only certain fibers allowing others to recover in the meantime.
The electrode in question includes a 1st branch that passes under the nerve and a 2nd that passes on it. The one that passes under the nerve comes out through a window created surgically under it; the matrix is held in place with sutures ensuring the contact with the nerve. On the other hand, the one that passes on the nerve is not maintained by it, and the contact of the contactors with the nerve is no longer assured. It is therefore necessary to use suture.
In addition the electrode in question is placed on each phrenic nerve (right and left) according to conventional invasive surgical practice (thoracotomy).
It therefore does not allow the use of trocar (no more than 10 mm in diameter) and, consequently, that of the video-controlled thoracoscopic technique, which is much less invasive.